Too Many Rooms on One Circuit?

I plugged a space heater in my livingroom and 20 minutes later all of the plugs on that one wall stopped working. Two days later, I decorated my outside with Christmas lights. One hour later the breaker tripped. I noticed the lights in all but 3 rooms in our house went out. Does this mean 6 rooms are running off that same breaker? Should it be that way? Also, can the breaker tripping cause a fire?

Did the lights in all the rooms come back on when you reset the breaker? If so, then they are all on the same breaker and in modern wiring practice that should not be done. We have so many different electrical items available now the rooms should be on seperate breakers (and wiring) to handle the load. The breaker tripping helps prevent fires, it cuts the power before the load can cause the wiring to overheat and cause a fire. I would get a licensed electrician to look at your wiring and give an estimate on updating it.